From DE 10 2012 200 623 A1 an exhaust gas turbocharger is known, which comprises a rotor and a bearing cartridge for mounting the rotor in a housing of the exhaust gas turbocharger. The rotor comprises a turbine wheel of a turbine of the exhaust gas turbocharger, a compressor wheel of a compressor of the exhaust gas turbocharger and a shaft, which is connected to the turbine wheel and to the compressor wheel in a rotationally fixed manner. The bearing cartridge comprises an inner sleeve that is coaxially arranged on the shaft axially between the turbine wheel and the compressor wheel in a rotationally fixed manner and an outer sleeve which is coaxial to said inner sleeve, which outer sleeve is rotatably mounted on the inner sleeve via rolling bodies. Furthermore, at least two damping rings are provided which are arranged coaxially on the outer sleeve and axially spaced from one another and which are supported on a bearing section of the housing. With the known exhaust gas turbocharger the damping rings are each formed by a coil spring, which in particular can be a stranded wire-type multiple wire coil spring produced from multiple individual wires.
Damping rings between the outer sleeve of the bearing cartridge and the bearing section of the housing are required in order to dampen undesirable oscillations of the rotor at natural frequencies of the rotor which are critical to bending.